1. Technical Field
The present invention relates generally to the field of audio systems for automotive vehicles, and, more specifically, to a programmable audio system wherein various signal processing settings in the radio receiver of the audio system can be customized to the particular vehicle in which the audio system is installed.
2. Background of the Invention
Virtually all modern automotive vehicles include an audio system that incorporates a radio receiver. A primary function of a radio receiver is to receive (through an antenna) radio signals transmitted over the airwaves, and then process and transform those radio signals into audio signals that can be provided to speakers, which in turn convert the audio signals into audible sounds. The nature of the audio signals provided by the receiver to the speakers determines, in large part, the audible sound output from the speakers. It is desirable for the radio receiver to optimize the audio signal so that the speakers produce the best possible audible sound.
Various well-known signal-processing techniques are applied to process and optimize the radio signal received by the receiver. For example, receivers typically employ a “blend” process to the input signal. “Blending” involves evaluating the strength of the radio signal received by the receiver and converting the audio signal supplied to the speakers from a stereo signal to a mono signal when the strength of the radio signal is relatively weak, which may occur when driving under a bridge, for example. After a given time constant, the receiver causes the audio signal to return to stereo. Receivers also typically employ a “roll-off” process to the radio signal, which involves phasing out higher frequencies in the radio signal so as to reduce the amount of undesirable noise produced by the speakers. Receivers also typically include a “noise blanker” process, which reduces the amount of noise/interference in the radio signal resulting from various vehicle noises, such as engine noise and stray reflections and signals. Several other signal-processing techniques are commonly employed by radio receivers to optimize the audio signal output to the speakers.
To achieve optimal audible sound from the vehicle audio system, it is desirable that the various signal-processing techniques of the receiver be adjusted to match the characteristics of the vehicle in which the radio receiver is installed. This is because many different vehicle-specific factors can affect the nature and quality of the radio signal received by the radio receiver and ultimately the quality of the audible sound produced by the speakers. Depending on these vehicle-specific characteristics, different degrees of “blending”, “roll-off”, “noise blanking”, and other signal-processing techniques may be desirable. For example, the shape of the vehicle body and the particular engine used in the vehicle may affect the quality of the radio signal received by the receiver. Similarly, the shape of the interior passenger compartment and the number and placement of speakers therein affect the quality of the audible sound heard by a passenger. Furthermore, person-specific listening preferences affect the perceived quality of the audible sound produced by the speakers. For instance, younger people tend to prefer to listen to higher frequency signals, whereas older people tend to prefer that the higher frequency signals be filtered out. As a result of these vehicle-specific characteristics and person-specific preferences, different degrees of “noise-blanking, “blending”, “roll-off”, and other signal-processing techniques may be desirable.
It is common to install the same radio receiver model in many different types of vehicles, each having different vehicle-specific characteristics that affect the quality of the audible sound produced by the audio system. Therefore, in an attempt to optimize the audible sound produced by the speakers, it is known to modify the various signal-processing algorithms in radio receivers during manufacture of the radio receiver to complement the particular vehicle in which the receiver is to be installed. Under this method, because the signal-processing techniques of radio receivers are optimized for each type of vehicle, each vehicle model may have a slightly different radio receiver associated with it, even though the same basic kind of radio receiver is installed in several vehicle models. The process of manufacturing several different versions of the same basic radio receiver results in an undesirable inventory of multiple part numbers. Therefore, this is a logistically-difficult and expensive solution to optimizing audio systems.
As a result, it is common to manufacture radio receivers used in different vehicle models such that their signal-processing algorithms are adjusted to complement the “average” characteristics of the various vehicles into which the receiver is to be installed. Thus, the radio receivers, while performing adequately for the various vehicle models, are not optimized for any particular vehicle model.
The inventors have recognized that the practice of optimizing radio receivers for the “average” vehicle characteristics across many different vehicle models, each having different vehicle-specific audio characteristics, does not produce optimal audio response for any of the vehicles. Instead, it is desirable to be able to optimize the signal-processing algorithms of radio receivers to complement the specific vehicle characteristics of the particular vehicle in which it is installed. Furthermore, the inventors have recognized that the known methods of optimizing the signal-processing algorithms do not provide for the ability to adjust the signal-processing algorithms after the radio receiver is installed in a vehicle to account for listener-specific listening preferences. Therefore, the inventors have recognized the need for a new system and method for optimizing the quality of radio signals for different vehicles that address the shortcomings of the prior art.